Re: [Xenomai] IRQ of pci express claimed by linux domain

[Henning Schild <henning.schild@siemens.com>]

On Fri, 12 Feb 2016 11:22:17 +0100
Wolfgang Netbal <wolfgang.netbal@sigmatek.at> wrote:

> Dear all,
> 
> I am using an imx6 controller where a FPGA-device is connected via
> PCI express.
> To use the FPGA in realtime I try to claim the IRQ 155 using 
> rtdm_irq_request() but the IRQ is hold by the linux domain.
> It looks like the default driver claims the IRQ, but I have my own 
> driver that is linked to the device if we can trust the output of
> lspci Has anyone of you an idea what could be the reason for this
> issue or an idea how to fix it ?

If you want to use another driver for the device you have to unload the
driver currently in use, afterwards you should be able to claim the
device in your driver.
At runtime you can unbind the driver and keep the module loaded, or
just unload the module. To avoid the driver taking control by default
you have to blacklist the module in your distro, or disable it in your
kernel config.

> 
>  > cat /proc/interrupts  
>             CPU0       CPU1       CPU2       CPU3
> ...
> 150:      39833          0          0          0       GIC
> 2188000.ethernet 151:          0          0          0
> 0       GIC 2188000.ethernet 155:          0          0
> 0          0       GIC  PCIe PME ...
> 
>  > lspci -v  
> 00:00.0 PCI bridge: Device 16c3:abcd (rev 01) (prog-if 00 [Normal
> decode]) Flags: bus master, fast devsel, latency 0
>      Memory at 01000000 (32-bit, non-prefetchable) [size=1M]
>      Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
>      Memory behind bridge: 01100000-012fffff
>      [virtual] Expansion ROM at 01300000 [disabled] [size=64K]
>      Capabilities: [40] Power Management version 3
>      Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
>      Capabilities: [70] Express Root Port (Slot-), MSI 00
>      Capabilities: [100] Advanced Error Reporting
>      Capabilities: [140] Virtual Channel
>      Kernel driver in use: pcieport
> 
> 01:00.0 ACCESS Bus: Device 5112:0c00
>      Subsystem: Device 5112:0c00
>      Flags: bus master, fast devsel, latency 0, IRQ 155
>      Memory at 01100000 (32-bit, non-prefetchable) [size=1M]
>      Memory at 01200000 (32-bit, non-prefetchable) [size=1M]
>      Capabilities: [40] Power Management version 3
>      Capabilities: [48] MSI: Enable- Count=1/1 Maskable- 64bit+
>      Capabilities: [58] Express Endpoint, MSI 00
>      Capabilities: [100] Device Serial Number 00-00-00-01-01-00-0a-35
>      Kernel driver in use: Sigmatek PCIE
> 
> 
> Kind regards
>